a. Field of the Invention
This invention relates to medical systems such as medical device navigation systems. Specifically, the instant invention relates to a system for registering a group of images of an anatomical region of a patient in a coordinate system of a medical system such as a medical device navigation system.
b. Background Art
It is desirable to track the position of medical devices as they are moved within a body so that, for example, drugs and other forms of treatment are administered at the proper location and medical procedures can be completed more efficiently and safely. One conventional means to track the position of medical devices within the body is fluoroscopic imaging. Fluoroscopy is disadvantageous, however, because it subjects the patient and clinician to undesirable levels of electromagnetic radiation. As a result, medical device navigation systems have been developed to track the position of medical devices within the body. These systems typically rely on the generation of electrical or magnetic fields and the detection of induced voltages and currents on position sensors attached to the medical device and/or external to the body. The information derived from these systems is then provided to a clinician through, for example, a visual display. Oftentimes, a representation of the medical device is displayed relative to a computer model or one or more images (including, but not limited to, fluoroscopic images) of the anatomical region in which the device is being maneuvered. In order to display the medical device at the correct location relative to the model or image, the model or image must be registered within the coordinate system of the navigation system.
Images may be registered in the coordinate system of a medical device navigation system in a variety of ways. If the imaging system used to capture the images is physically integrated with the navigation system, as described in commonly assigned U.S. patent application Ser. No. 11/971,004, the entire disclosure of which is incorporated herein by reference, the imaging system can be registered with the navigation system during installation and the spatial relationship of the navigation system to the imaging system is thereafter constant and known, obviating the need for registration during each new procedure. Where the navigation system and imaging system are physically separate, however, the changing spatial relationship of the systems makes registration more complicated. One solution is to place a plurality of radiopaque fiducial markers in the field of view of the imaging system at locations known relative to the coordinate system of the navigation system. Because the markers are visible in images produced by the imaging system, the images can be registered with the coordinate system by reconciling the visible location of each marker in the images with that marker's known location in the navigation coordinate system. One drawback to this solution, however, is that the fiducial markers are typically visible in the images seen by the clinician performing the procedure, potentially interfering with the clinician's view of the anatomical region being imaged.
The inventors herein have recognized a need for a system and method for registering a group of images of an anatomical region of a patient in a coordinate system of a medical device navigation system that will minimize and/or eliminate one or more of the above-identified deficiencies.